linux-kernel - Re: [v7 5/5] mm, oom: cgroup v2 mount option to disable cgroup-aware OOM killer

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Message-ID: <20170907145239.GA19022@castle.DHCP.thefacebook.com>
Date:   Thu, 7 Sep 2017 15:52:39 +0100
From:   Roman Gushchin <guro@...com>
To:     Christopher Lameter <cl@...ux.com>
CC:     David Rientjes <rientjes@...gle.com>, <nzimmer@....com>,
        <holt@....com>, Michal Hocko <mhocko@...nel.org>,
        <linux-mm@...ck.org>, Vladimir Davydov <vdavydov.dev@...il.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tejun Heo <tj@...nel.org>, <kernel-team@...com>,
        <cgroups@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <sivanich@....com>
Subject: Re: [v7 5/5] mm, oom: cgroup v2 mount option to disable cgroup-aware
 OOM killer

On Thu, Sep 07, 2017 at 09:43:30AM -0500, Christopher Lameter wrote:
> On Wed, 6 Sep 2017, David Rientjes wrote:
> 
> > > The oom_kill_allocating_task sysctl which causes the OOM killer
> > > to simple kill the allocating task is useless. Killing the random
> > > task is not the best idea.
> > >
> > > Nobody likes it, and hopefully nobody uses it.
> > > We want to completely deprecate it at some point.
> > >
> >
> > SGI required it when it was introduced simply to avoid the very expensive
> > tasklist scan.  Adding Christoph Lameter to the cc since he was involved
> > back then.
> 
> Really? From what I know and worked on way back when: The reason was to be
> able to contain the affected application in a cpuset. Multiple apps may
> have been running in multiple cpusets on a large NUMA machine and the OOM
> condition in one cpuset should not affect the other. It also helped to
> isolate the application behavior causing the oom in numerous cases.
> 
> Doesnt this requirement transfer to cgroups in the same way?

We have per-node memory stats and plan to use them during the OOM victim
selection. Hopefully it can help.

> 
> Left SGI in 2008 so adding Dimitri who may know about the current
> situation. Robin Holt also left SGI as far as I know.

Thanks!